Wide bandgap (WBG) gallium nitride (GaN) based power electronic devices are gaining importance as next generation high-efficiency power devices owing to superior material properties such as high electric breakdown field, high electron saturation velocity, and high electron mobility in a readily available heterojunction 2-D electron gas (2DEG) channel. With this technology it is possible to achieve much higher power density as well as efficiency for power electronic devices.
At present, available GaN platforms include GaN on silicon, GaN on sapphire, and GaN on GaN. Regardless the substrate material used, a common challenge is the mismatch of the gate driving voltage, being much lower than its silicon counterpart, making it difficult to directly replace silicon MOSFETs or IGBTs in existing power electronic systems. A lower gate driving voltage makes GaN devices less immune to driving voltage noise and thus reduces system reliability.
One common solution for overcoming this mismatch is to use low voltage MOSFETs as the front end in a cascade configuration. However, such an approach suffers from mismatch of channel leakage currents between the two different transistors, which degrades the reliability and performance of such cascaded devices compared to high electron mobility transistor (HEMT) counterparts.